Hydraulic Clutch Actuation Systems for Light Trucks 2007-01-2564

The clutch actuation system is directly linked to vehicle easy of operation and ergonomics. For passenger cars, a comfortable pedal force is considered light when it is under 100 N and hard if over 130 N. For Commercial vehicles, about 170 N are considered acceptable. This work looks forward to obtain a pedal curve in Excel which simulates the real one and can low down actuation systems developing time. For in such way, it points to cares about master cylinder actuation geometry, stroke and pedal effort variations in the way that it is comfortable for the driver, works on low hydraulic pressure and is able to keep functionality during whole clutch plate and disc life. Some calculations about lever and master cylinder push rod dimensions are realized in the way of keeping actuation angles drawing limits. Empirical evaluations about losses in components (hydraulic and mechanical) for determination of stroke of pedal and pedal effort actuation are also done. The need of an over center spring to low down pedal effort is also point of discussion, determining compromise between product costs and easy of operation. This paper leads to a virtual curve which relates pedal effort with pedal stroke and is composed from system and over center spring curve.